package org.example.ch02.p28;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int score=sc.nextInt();
        char grade;
        if (score<60){
            grade='E';
        }else if(score<70){
            grade='D';
        }else if(score<80){
            grade='C';
        }else if(score<90){
            grade='B';
        }else{
            grade='A';
        }
        System.out.println(grade);
        sc.close();
    }
}
